An escape character is a character that causes one or more characters that follow it to be interpreted differently. This forms an escape sequence, which is often used to represent a character that has an alternative meaning when printed literally, such as the quote character in a string literal. Escape sequences can have other usages too, especially in regular expressions.
\) to escape characters like \', \", \u0026, etc.\) to escape characters like \\, \n, \26, etc. See escape characters for more information.<, <, or <.%) to escape characters like %20, %3C, %3E, etc.